Apparatus for producing and conditioning chemical mixtures



May 22, 1962 R. KURZ 3,035,902

APPARATUS FOR PRODUCING AND CONDITIONING CHEMICAL MIXTURES OriginalFiled April 5, 1957 HIHIHIHHIIIIHI INVENTOR. Rainer Kurz ATTORNEYS.

United States Patent 3,035,902 APPARATUS FOR PRODUCING AND CONDI-TIONING CHEMICAL MIXTURES Rainer Kurz, Olgastrasse 6, Stuttgart-Stammheim, Germany Original application Apr. 5, 1957, Ser. No. 651,109.Divided and this application Feb. 6, 1958, Ser. No. 718,104

Claims priority, application Germany Apr. 6, 1956 2 Claims. (Cl. 23252)This application is a divisional application of U5. Serial No. 651,109,now abandoned. This invention relates to liquid chemical compositionsand mixtures of the kind which are adapted to harden after apredetermined period, for example, after having been applied to a basematerial, and is particularly concerned with coating compositions suchas lacquers and varnishes and apparatus for preparing, conditioning andapplying such compositions or mixtures.

While the invention is generally concerned with chemical compositions ofmixtures of the kind referred to, the invention will be described andexplained in the following with particular reference to so calledreaction lacquers or reaction varnishes, that is, lacquers or varnishescomprising a mixture of at least two components which latter chemicallyreact with each other, usually under development of exothermic heat, toform a hardened material or protective coating. Such mixtures willhereinafter be referred to as reaction mixtures.

It is common practice that the components of such liquid reactionmixtures, which are adapted to form hard protective coatings, are mixedin a predetermined ratio in a pot or container prior to being applied tothe base material, whereafter the liquid reaction mixture has to beworked up within a predetermined time period. It is of course, mostessential that the liquid reaction mixture obtained after mixing thecomponents is worked up and applied to the base material in liquidstate, i.e., prior to the complete hardening of the reaction mixture.This time period within which the liquid reaction mixture has to beworked up and applied to the base material, is usually referred to aspot time.

With a view to extending the pot time of the liquid reaction mixture, itis customary to admix the reaction mixture with solvents, whereby,however, the reaction mixture becomes rather diluted. This in turn makesit diflicult to obtain a thick coat on the base material. In any case,the addition of the solvents makes it rather impossible to obtain thickcoats with one single application or working step. Further, thehardening time of the coating composition or reaction mixture isprolonged due to the presence of the solvents which first have toevaporate after the reaction mixture has been applied to the basematerial.

A further drawback of customary methods for the preparation andapplication of reaction mixtures resides in the fact that normally thehardening of the reaction mixture after its application to the basematerial is very slow at low temperatures. In some cases the reactionmixture does not harden at all. If on the other hand, chemicalcomponents are added to the reaction mixture with a view to inducing thehardening, i.e., if one adds components having a high hardeningactivity, then this may result in a drastically reduced pot time, sothat the working up of the reaction mixture and the applying of thereaction mixture onto the base material has to be effected within a veryshort time.

It is an object of this invention to provide an apparatus by means ofwhich the pot time of the reaction mixtures or reaction lacquers can beconditioned, and by which the drawbacks above referred to may beovercome.

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The invention is based on the consideration that the reaction mixtureshould be applied to the base material on the one hand at a time atwhich the reaction mixture has already hardened to such an extent thatthe final hardening to obtain the finished coat is rather short and onthe other hand at a time at which it is still sufiiciently viscous so asto enable an easy application.

In accordance with this invention, the components of the reactionmixture are mixed prior to being worked up or applied to the basematerial and are thereafter, prior to hardening, subjected to atemperature conditioning treatment which is carefully controlled withregard to time and temperature.

By subjecting the reaction mix-ture prior to its hardening and prior toits application to the base material to such conditioning treatment, thepot time can be considerably prolonged, while the hardening time of thereaction mixture after its application onto the base material may beconsiderably shortened. In carrying out the conditioning treatment it isvery important to carefully control and choose the treatment time andtemperature. These two factors, that is, the time and temperatures ofthe conditioning obviously will have to be varied in accordance with thenature of the components of the reascertained that the final hardeningof the reaction mixture, after its application onto the base materialcan be effected at low temperatures, if the preceding condition- 1 ingtreatment has lasted sufiiciently long. If the reaction between thecomponents of the reaction mixture has progressed to a stage which isnear the end of the reaction, then, it has been found, the finalhardening will successfully take place at relatively low temperatures.Thus, it has been found that a reaction mixture which did not harden atzero degree centigrade Without being subjected to an inventiveconditioning treatment, did harden within three hours at thistemperature, if subjected to a preceding conditioning treatment.

In this connection, it is pointed out that the term conditioningtreatment as used in this application covers both heating and cooling ofthe reaction mixture. In other words, the reaction between thecomponents of the reaction mixture might be conditioned by eitherheating or cooling the reaction mixture, or the mixture may first beheated and then cooled. This will depend on the nature of the reactants.It will be readily understood that in some cases the reaction betweenthe components might be so vigorous that the pot time or hardening timeof the mixture is very short. Thus, in order to prolong the pot time andthus the hardening time, it will be required to slow down the reactionvelocity between the components.

The inventive apparatus will be more fully understood from the followingdescription and drawing which is a somewhat diagrammatical view of apreferred embodiment thereof.

Referring now to the drawing, the apparatus here illustrated comprises asupply line 1 which connects a storage container (not shown) to thismixing chamber or valve 4. A second supply line 2 connects a secondstorage con-v tainer (not shown) to this mixing chamber or valve 4. Athree-way cock 3 is fitted in the line 2. A coil-shaped pipe 6 connectsthe mixing chamber 4 to ejecting means in the form of a spraying nozzle11. The coil-shaped pipe 6 is housed in a casing which is provided witha thermostatically controlled heating element 8. A further threeway cock9 is connected in line 6 at the outlet end thereof. A pipe connects thenozzle T1 to a supply of compressed air (not shown). The line 5 forconducting'compressed air to the nozzle 11 is in heat exchanging contactwith the casing through heat exchanger 7. The heat exchanger 7 isprovided on the casing for facilitating heat exchange between the casingand the line 5. Afurther cock 12 is operatively connected in line 5 tocontrol flow from line 5 m the three-way cock 9. A return pipe connectsthe outlet side of the coiled pipe 6 to the first mentioned storagecontainer (not shown). The flow through the return pipe ltlis controlledby the three-way cock 9.

The apparatus shown in the drawing is adapted for conditioning reactionor coating mixtures or the like, comprising two cornponents. Theoperation of the apparatus is as follows. The two components of thisreaction mixture are separately supplied to the mixing chamber 4 throughlines 1 and 2, respectively. Under certain circumstances, thecomponents, which are supplied through the lines 1 and 2 may bepro-heated. This depends on the nature of the particular components. Thecomponents are mixed in chamber 4 and the mixture is then fed to thecoiled pipe 6 which acts as a delaying means or receiver in which thereaction between the components of the mixture takes place. The pipe 6,as previously pointed out, is accommodated within the casing which isprovided with the thermostatically controlled heating element 8. Thetemperature within the casing and thus within the coiled pipe 6 can thusbe carefully controlled. Further, the coiled pipe has a definite lengthand a definite diameter. The length of pipe 6 and the, throughputveiocity through this pipe determine the speed of the reaction betweenthe components of the reaction mixture fed from mixing chamber 4. Themixture finally reaches the nozzle 11 through which it is sprayed ontothe base material (not shown). It will be realized that the mixturemight be sprayed through the nozzle 11 directly onto a base material,or, if desired, the mixture first may be supplied to an intermediatecontainer or vessel from which the mixture is then taken in order to beapplied onto the base material.

The spraying, that is the discharge of the reaction mixture from thenozzle 11 should preferably be intermittent.

7 During the intermissions, a further amount of one of the components ofthe mixture may then be supplied through supply line 1 or 2 and into thecoiled pipe 6. This component flows through the three-way cock 9 and thereturn line 10 back into the storage container (not shown) from whichthe component originally was taken. The reason for this last mentionedmeasure is the following: Since at any given moment a certain amount ofmixture will remain in the coiled pipe 6, it is necessary to appiymeasures to prevent the hardening of this mixture in the coiled pipe 6.It now a further amount of one of the components is fed through one ofthe supply lines during 7 the intermissions of the spraying process, theratio between the two components in the coiled pipe 6, will be altered,so as to prevent undesired hardening therein.

At the end of the spraying process, it is also possible to accomplish aseparation of the components in the mixing chamber or nozzle 4 therebythat air is blown into the system through the three-way cock 3.

If the spraying process takes a rather long time, the

. coiled pipe Will be heated to a temperature by the reaction mixture,which temperature is in excess to that of the starting temperature. Thisin turn results in a shortening of the hardening time and might thuslead to the hardmixture is within the coiled pipe 6. It will be observedthat the further line 5, previously referred to, is provided, which line5 is in heat exchanging contact with the casing through the heatexchanger 7. The line 5 serves primarily the purpose to conductcompressed air to the nozzle 11 which compressed air is used forefiecting the spraying. By properly adjusting the three-way cock 9 andthe cock or valve 12, this compressed air might also be used to cool themixture within the coiled pipe 6. Thus, when air passes through line 5,a certain amount of heat will be dissipated from the casing housing pipe6 by means of the heat exchanger 7.

in order to obtain faultless functioning of the apparatus shown in thedrawing, it is advantageous to actuate the two-way cock 3 and thethree-way cock 9, which latter is coupled with the cock 12 in the airline 5, in a predetermined time sequence. This may be done in automaticmanner thereby that the cocks are controlled and actuated by means of atiming device i.e., time switch (not shown) or the like. This timingdevice (not shown) may advantageously be driven or actuated by a turbinewhich works on compressed air.

I have described preferred embodiments of my invention, but it should beunderstood that this disclosure is for the purpose of illustration, andthat various omissions and changes in shape, proportion arrangements ofparts, as well as the substitution of equivalent elements for thearrangements shown and described may be made without departing in anyway from the scope and spirit of the invention as recited in theappended claims.

I claim:

1. An apparatus for preparing and conditioning a liquid chemical mixturewhich is adapted to harden after discharge from said apparatus,comprising in combination:

' mixing means for preparing said chemical mixture therein, conveyingmeans leading to said mixing means and including at least two supplylines adapted separately to conduct at least two reactive components tosaid mixing means, a first air line operatively connected to one of saidsupply lines for blowing air therethrough when it is desired to emptythe supply line of said component, first valve means arranged betweensaid first air line and said one supply line for alternativelyconnecting and disconnecting said air line and said supply line, acasing, a coiled pipe at least partly accommodated in said casing andhaving its inlet side operatively connected with said mixing meansfor'admitting said mixture thereto, adjustable heating means arranged insaid casing for controlling the temperature of said mixture in saidcoiled pipe so as to influence the final hardening time of said mixture,ejecting means situated at the outlet side of said coiled pipe, a returnline operatively connected to the outlet side of said coiled pipe and toat least one of said supply lines, when it is desired to pass onereaction component out of said coil and back to its supply line, secondvalve means for controlling flow through said return line, a second airline for supplying compressed air to said ejecting means, andvalve-controlled connecting means for connecting said second air line tothe outlet side of said coiled pipe..

2. In an apparatus as claimed in claim 1, heat exchanger means providedbetween said casing and said second air line for conditioning thetemperature of and in said coiled pipe.

References Cited in the file of this pat ent UNITED STATES PATENTS2,511,626 Einbecker June 13, 1950 2,513,081 Clark June 27, 19502,579,357 Arvedlund Dec. 18, 1951 2,764,565 Hoppe et all Sept. 25, 19562,779,689 Reis Jan. 29, 1957

1. AN APPARATUS FOR PREPARING AND CINDITIONAL A LIQUID CHEMICAL MIXTUREWHICH IS ADAPTED TI HARDEN AFTER DISCHARGE FROM SAID APPARATUS,COMPRISING IN COMBINATION: MIXING MEANS FOR PREPARING SAID CHEMICALMIXTURE THEREIN, CONVEYING MEANS LEADING TO SAID CHEMICAL MIXTURETHEREINCLUDING AT LEAST TWO SUPPLY LINES ADAPTED SEPARATELY TO CONDUCTAT LEAST TWO RELATIVE COMPONENTS TO SAID MIXING MEANS, A FIRST AIR LINEOPERATIVELY CONNECTED TO ONE OF SAID SUPPLY LINES FOR BLOWING AIRTHERETHROUGH WHEN IT IS DESIRED TO EMPTY THE SUPPLY LINE, A CASING, AVALVE MEANS ARRANGED BETWEEN SAID FIRST AIR LINE AND SAID ONE SUPPLYLINE FOR ALTERNATIVELY CONNECTING AND DISCONNECTING SAID AIR LINE ANDSAID SUPPLY LINE, A CASING, A COILED PIPE AT, LEAST PARTLY ACCOMMODATEIN SAID CASING AND HAVING ITS INLET SIDE OPERATIVELY CONNECTED WITH SAIDMIXING MEANS FOR ADMITTING SAID MIXTURE THERETO, ADJUSTABLE HEATINGMEANS ARRANGED IN SAID MIXTURE IN SAID COILED TROLLING THE TEMPERATUREOF SAID MIXTURE IN SAID COILED PIPE SO AS TO INFLUENCE THE FINALHARDENING TIME OF SAID MIXTURE, EJECTING MEANS SITUATED AT THE OUTLETSIDE OF SAID COILED PIPE, A RETURN LINE OPERATIVELY CONNECTED TO THEOUTLET SIDE OF SAID COILED PIPE AND TO AT LEAST ONE OF SAID SUPPLYLINES, WHEN IT IS DESIRED TO PASS ONE REACTION COMPONENT OUT OF SAIDCOIL AND BACK TO ITS SUPPLY LINE, SECOND VALVE MEANS FOR CONTROLLINGFLOE THROUGH SAID RETURN LINE, A SECOND AIR LINE FOR SUPPLYINGCOMPRESSED AIR TO SAID EJECTING MEANS, AND VALVE-CONTROLLED CONNECTINGMEANS FOR CONNECTING SAID SECOND AIR LINE TO THE OUTLET SIDE OF SAIDCOILED PIPE.